Thesis Archive
Alkali-Catalyzed Transesterification of Waste Cooking Oil (WCO) by Conventional Heating (2011)
Concepcion, Aliza V.
Jardin, Kimberly P.
Razon, Jerica Marise M.
Abstract:
-“Biodiesel is usually produced from three types of feedstock: edible oil non-edible oil and now, waste cooking oil (WCO). WCO was chosen for this study because it is readily available, cheaper, doesn’t compete with the food industry with the consumption and land for plantation, doesn’t require planting and harvesting and lastly, it also contributes to the waste disposal solution of WCO making the production process more beneficial and environmentally friendly. Since WCO have been subjected to frying it had already undergone various physical and chemical changes in its properties. Thus, WCO are known to have higher free-fatty acid (FFA) and moisture content which needs to be treated and that is why pretreatment, specifically filtration and esterification, was done prior to transesterification reaction in this study. The purpose of this study was to compare the yields of the biodiesel produced from Restaurants A and B using methanol and ethanol as alcohol in the transesterification reaction. The free-fatty acid (FFA) was first lowered by acid-catalyzed esterification. The lowest FFA content obtained for sample A and B were 0.42 and 0.27 mgKOH/ g oil, respectively. For the transesterification process, this was done by conventional heating using potassium hydroxide and sodium hydroxide as the catalysts and methanol and ethanol as the alcohols. The parameters considered for this process were reaction time (30, 45, 60, and 75 min), alcohol to oil ratio (6:1, 7:1 and 9:1), reaction temperature (60 and 70°C) and catalyst concentration (0.75, 1.0 and 1.5%). From the results obtained from the experiments performed, the effect of the main parameters, alcohol to oil ratio, catalyst concentration and reaction time on the yield of biodiesel were obtained. The alcohol to oil ratio and catalyst concentration were observed to have a negative influence on the biodiesel yield. The graphs of the reaction time parameter using methanol as alcohol did not change considerably with time. However, the graph of the reaction time parameter using ethanol decreased at a certain point due to the backward reaction that occurred in ethanolysis. In general, a higher yield was obtained when methanol was the alcohol used compared to that of ethanol. On the other hand, high yield values were obtained using potassium hydroxide catalyst than that of when sodium hydroxide was used. The physical properties of the biodiesel produced were obtained using ethanol and methanol for each of the two sources, source A and source B. These four samples were chosen based on the purity which was obtained from the results of the total glycerol analysis. The density of the samples that was produced when methanol was used in the reaction were 0.8910 kg/L and 0.8870 kg/L for Oil A and Oil B respectively which were within the limit of the PNS standard. The samples produced using ethanol failed meet the standard due to the presence of unreacted oil because of the incomplete transesterfication. All four samples failed to meet the PNS standard for the kinematic viscosity due to the formation of emulsions in the biodiesel product caused by the use of 1.5% NaOH catalyst. The high viscosity of the produced ethyl esters compared to methyl esters were attributed to the incomplete ethanolysis of WCO. All four samples met the flash point standards which were greater than 100°C. “
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